Electric plug



Au .'31, 194s. c. H. boLAN, 2D

ELECTRIC PLUG Filed Dec. 28, 1944 1 n 9 75 WWW/Al i all 1 H T m 6 5 W Fl G4:

C'l/A RLEHBOLA N 17 INVENTOR.

Evy MW ATTORNEY particular reference Patented Aug. 31, 1948 UNITED s TATES PATENT v OFFICE Charles 11. Digitizin Conn. Application December 28, 1944, Serial lVo. 570,049

' 3 Claims. (01. 173-361) I v My invention relates to electric plugs and has to plugs having prongs adapted to be inserted in sockets for connecting electric cords from electric appliances with a source of current.

In certain respects. the present invention is.

to be considered as presenting a commercially and functionally improved structure over that included in my prior application having Serial No. 499,965 and which was :flled on August 25, 1943.

Ordinary electric plugs have a disadvantage in that they can be easily pulled out when the cord, which extends directly outwards from the plug, is caught by somecnes foot or by a piece of furniture being moved about. Moreover, the cord, extending from the plug, is naturally frequently used for. pulling the plug out of a socket witha result, that the connections between the cord and the contact screws in the plug become loosened and the wires may even break. My invention therefore has for one of its objects to provide a plug so arranged that the cord extends from the side of the plug so that it cannot be used for pulling the plug out 01' its socket, and the cord can be conveniently placed alongside the wall near the socket where it is out of the way. 1

Another disadvantageof the ordinary plug is that they require considerable-force to pull them out of the sockets, due to the necessity to provide good electrical contacts between the prongs of the plug and the corresponding seats for them in the sockets. In my improved plug I eliminate this dis-advantage by providing a releasing member which smoothly and evenly disengages the plug from the sockets by a simple operation of pushing the releasing member inwards thereby raising the plug from its seat on the socket. The operation can be conveniently performed by holding the plug between the index i and middle fingers and pushing the releasing member inwards by the thumb.

As a further improvement of my plug, I provide the releasing member with an enlargement at the end whereby the releasing member, when moved into an inoperative position by the plug being inserted into the socket, engages the inner sides of the prongs and causes the prongs to move outwards into a firm engagement with the corresponding contact member in the socket thereby establishing a good electrical contact and, at the same time, providing for a firm mechanical engagement of the prongs by the sockets in the receptacle.

Other objects, features and advantages of my plug are more fully explained in the accompanying specification and drawing in which- Fig. i is a sectional view of my plug in an operative position, inserted in a socket;

Fig. 2 is a bottom plan view of the same;

Fig. 3 is a sectional view taken on the line H of Fig. 2 showing the plug in an inoperative position. withdrawn from the socket;

Fig. 4 is a sectional view of aimodified plug in an operative position;

Fig. 5 is'a similar view of the modified plug in an inoperative position, withdrawn from the receptacle.

My electric plug as shown in Figs. 1, 2 and 3, consists of a body I made of an insulating material such as"Bakelite or similar-plastic. A recess 2 is provided at the bottom of the body I for prongs 3. Each prong is made of a strip of a resilient metal which is a good conductor of electricity, the ends of the strip being bent outward at I and i and provided with screws 1 for attaching the ends of insulated wires 8, 9 Joined together into a cord In which extends outside of the plug through a hole II in theside oi the body I. A tongue l is provided on the left prong for retaining the cord behind the screws 1.

The body I is provided with a central hole I! ior a, releasing plunger I 3 which slides freely in the hole I2 and is limited in its movement by an enlargement I 4 at the lower or inner end and an enlargement II at the upper or outer end. A recess I8 is provided in the upper portion of the body I for the enlarged head It of the plunger. p

The plug is inserted in its place in a receptacle in the same manner as any ordinary or conventional plug, by placing the prongs 3 into the corresponding holes in the receptacle and pressing against the body I until the prongs are rully inserted. The plunger I3 is then automatically moved outwards when its lower end engages the surface of the receptacle. The plugis shown in Fig. 1 in its operative or inserted position. The lower enlargement J4 in this position engages inner humps ,I 8 of the prongs therey pressing the prongs outwards into a strong frictional engagement with the sides of the sockets lin-the receptacle. The prongs, being thus firmly pressed against the sides of the sockets in the receptacle, provide a good electrical contact, eliminating any danger ofhealting of the contact sm'i'aces, and also providing a strong mechanical engagement between the plug and'the socket.

I 3 preventing any possibility of an accidental pulling out of the plug.

For removing the plug it is only necessary to take hold of its neck portion l9 by the middle and index fingers and to press the plunger l3 downwards by the thumb. The plunger, while moving downwards, will raise the body I from the socket, at the same time releasing the outward pressure on the prongs so that the latter will be relatively free from the sockets in the receptacle. The plug will be thus removed easily and without any such efforts as are required with conventional plugs. I

A modified plug is shown in Figs. 4 and 5 in which the plunger is operated by a separate cap 20. The upper end of the plunger 2| is provided with a pin 22 engaging slots 23 in levers 24. The other ends of the levers are pivoted at 25 to the sides of the cap 20, the middle portions of the levers being pivotally connected at 28 to posts 21 extending from the body 28 of the plug.

The plug is inserted in the receptacle by applying pressure to the cap 20 thereby raising the plunger 2| and freeing the prongs 3. For removing the plug, ing the levers 24 to rotate on their fulcrums 26 and to move the plunger 2| downwards against the surface oithe receptacle, thereby moving the body 28 away from the receptacle.

It will be understood that various features and principles of each of the embodiments of the invention above described or referred to may be utilized or substituted in the other embodiments.

While the invention has been described in detail with respect to certain particular preferred examples, it will be understood by those skilled in the art after understanding the invention, that various changes and further modifications may .be made without departing from the spirit and scope of the invention, and it is intended therefore in the appended claims to cover all such changes and modifications.

What is claimed as new and desired to be secured by Letters Patent is:

1. An electric plug comprising a body made of an insulating material having an axially extending central opening and a reduced neck portion; resilient prongs parallel to the axis of the plug extending from the inner side of the plug for engagement with corresponding sockets in a receptacle; a plunger slidably supportedin the central opening adapted to be engaged by an operator's thumb while the neck of the body is held by the operators index and middle fingers for moving the plunger inwards thereby removing the plug from the receptacle; and means on the plunger to yieldably move the prongs sidewise the cap 20 is pulled outwards, causlel to the prongs; a plunger for engaging the sides of the sockets in the receptacle when the plunger is in its extreme outward position and the prongs are inserted into the sockets.

2. An electric plug comprising a bod made of an insulating material and having an axially extending central opening; resilient prongs extending from the body for engagement with sockets in a receptacle, the body having an opening extending axially in a direction substantially paralslidably supported in the opening having an enlarged head arranged to be manually moved inwards for engaging the surface of thereceptacle, thereby moving the plug away from the receptacle, the plunger having an enlargement at its inner end engaging the prongs when the plunger is withdrawn outwards by the pressure against the receptacle, thereby causing the prongs to frlctionally engage the sides of thesockets in the receptacle.

3. An electric plug comprising a body made of aninsulating material and having an axially extending central opening; prongs extending from the body for engagement with sockets in a receptacle, the bod having an opening extending axially in a direction substantially parallel to the prongs; and a plunger slidably supported in the opening and arranged to be moved inwards for removing the plug from the receptacle, the prongs being formed of resilient metal strips doubly bent upon themselves thereby forming rounded ends for insertion into the sockets of the receptacle, one outer end of each strip being secured inside the body, the inner end being bent at right angles and slidably supported inside the body, the plunger having an enlargement at the inner end for engaging the inner portion of the strips and for pressing the strips against the sides of the sockets when the prongs are fully inserted therein.

CHARLES H. DOLAN, 11.,

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Cornwall Nov. 4, 1941 

